1. Field of the Invention
The invention relates to an image processor that can provide ensured visibility even under direct sunlight.
2. Description of the Background Art
Conventionally-known image display apparatus included in a car navigation system or the like display navigation data to navigate to a destination, DTV (Digital Television) broadcast, or an image captured by an in-vehicle camera on the display apparatus screen.
Such image display apparatus correct an image so as to ensure visibility of the displayed image on the display screen which is exposed to outside light.
One of the well-known technologies for correcting an image in such a case is to correct contrast, luminance of a backlight and others in accordance with illuminance of outside light detected by an illuminometer. Generally, an image processing circuit included in image display apparatus implements such image correction.
The image display apparatus performs a stronger correction when it is exposed to stronger outside light such as direct sunlight. In many cases, the image on which such a stronger correction has been performed shows an incongruity in color tone compared to the original image before the correction. Therefore, the image display apparatus generally performs a moderate correction not to show such an incongruity.
However, in the technology described above, since the correction is controlled so that the incongruity is not shown regardless of the type of an input image, there are some cases where visibility of the display image cannot be ensured, while ensuring the visibility has to be given priority. An example of such a case is seen when the existence of a pedestrian or an obstacle near a vehicle has to be confirmed based on the image obtained by an in-vehicle camera.
Therefore, the subject is how to provide the ensured visibility of the display image even under direct sunlight, especially in the case of display of the input image requiring the ensured visibility.